Differentially expressed genes after treatment with hydroxytyrosol in DMBA-induced rat breast tumors
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ABSTRACT: The aim of this study was to compare the gene expression profile changes of DMBA-induced rat breast tumors after treatment with hydroxytyrosol (a natural compound from virgin olive oil). To this end, a cDNA microarray experiment was performed (Affymetrix’s Rat Genome 230 2.0 array). This gene expression study was carried out on the tumor biopsy samples prior to hydroxytyrosol treatment, and compared with matched tumor biopsy samples after completion of the hydroxytyrosol treatment schedule. The result of this study was the identification of several genes related to apoptosis, cell cycle arrest, proliferation, differentiation, survival and transformation-related genes. Breast tumors were induced with a single oral dose of 7,12-dimethylbenz(alpha)anthracene (100 mg/kg body weight) in female Sprague-Dawley rats to test the antitumor power of orally administrated hydroxytyrosol (0.5 mg/kg body weight 5 days/week for 6 weeks). Gene expression analysis was performed in paired samples as follows: HT final trucut tumor vs initial trucut tumor (HT final vs basal). For this assay, 5 samples were chosen according to histopathologic criteria (Bloom-Richardson grade II). Gene expression profiling was carried out using Affymetrix’s GeneChip technology, using the Rat Genome 230 v2.0 array from this provider. All the protocols and apparatus were recommended by Affymetrix. Total RNA from frozen mammary tumors was extracted by RNeasy Mini kit and homogenized by QIAshredder columns according to manufacturer’s instructions. The quality and quantity of the obtained RNA was checked out through agarose electrophoresis and later spectrophotometry at 260/280 nm. Biotinylated cRNA was synthesized following the IVT labeling kit from Affymetrix and purified by the GeneChip Sample Cleanup Module from Affymetrix. The quality and quantity of the obtained cRNA was again checked out through agarose electrophoresis and posterior spectrophotometry at 260/280 nm. After hybridization, slides were washed and scanned following the manufacturer’s standard protocol. Intensity values were normalized by Robust Multichip Average method and subsequently these were filtered to remove the control sequences and those with a hybridization signal close to background. The spike controls were: BioB, BioC, BioD and Cre; because BioB was the least abundant in the samples, it was used to estimate the sensitivity of the experiment. The housekeeping control was GAPDH. After non-supervised clustering using Pearson correlation coefficient, statistical significance of gene expression was estimated by Student’s T test for paired samples using GeneSpring GX 7.3 software (Agilent).
ORGANISM(S): Rattus norvegicus
SUBMITTER: Sergio Granados
PROVIDER: E-GEOD-15944 | biostudies-arrayexpress |
REPOSITORIES: biostudies-arrayexpress
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